Importing from Corel Dream 3D?
A little history followed by an educated guess...

CorelDream 3D was also sold as Ray Dream Designer and RDD is still a product owned by DAZ Productions, but it's sold under the name Carrara.

So, what I'm thinking is if any software still loads that file format, it would be one of the DAZ 3D products. You may even luck out and find that it'll load into Daz Studio which is free. If there's a demo version of Carrara, you might be able to load/export it from there if the demo version allows exporting. From there, you could export it as a Wavefront .obj file and bring it into Blender.

Failing that, if you can still get CorelDream 3D to run, load the model and do screenshots of front, side, top, etc. and load the screenshots as image planes into Blender and redo the model. Of course, if it's terribly complex, it may take some time.

Not a definitive answer, I know. I went down this same road with models from Sculpt-Animate 4D. Yeah, I know, nobody remembers that one :) I ended up recreating the models from scratch in Blender which didn't take nearly as long as I thought it would.

I hope you find a solution and that this has helped in at least some small way.